Astronomical evidence
HR 8799 e is one of the directly imaged giant planets around the young star HR 8799. Unlike a transit measurement, direct imaging separates planetary light from the much brighter host. A young giant can be bright in the infrared because it is still releasing internal heat. The GRAVITY instrument combined light from the Very Large Telescope Interferometer to obtain precise position measurements and a K-band spectrum. Atmospheric modeling indicated substantial carbon monoxide and cloud opacity associated with iron and silicate particles. The interpretation connects observed light to temperature, composition and vertical mixing. Direct detection does not mean a detailed photograph of the planetary disk. The planet’s radius, gravity and mass depend on model interpretation; the saved catalog mass estimate has a particularly broad uncertainty. The observations constrain a distant luminous atmosphere, not mountains or moon surfaces.
The illustrated viewpoint
Branching pentaradial reef organism in a still, inward-folded meditative pose. An unconfirmed fictional icy moon of a directly imaged giant. The icy foreground belongs to an invented moon. The giant’s ember coloring translates its thermal character into visible artwork and is not a calibrated human-eye view. The moon, ice and local sky brightness remain speculative.
The icy foreground belongs to an invented moon. The giant’s ember coloring translates its thermal character into visible artwork and is not a calibrated human-eye view. The moon, ice and local sky brightness remain speculative. All depicted life is fictional. The visual connection to the cosmos is an artistic theme, not a claimed biological mechanism.
Catalog measurements & sources
Host: HR 8799. Snapshot: 25 September 2026. Errors, limits and source provenance are retained. Calculated values and model estimates are not direct measurements. Unknown is not zero; equilibrium temperature is not surface temperature.
| Quantity / unit | Value / reported errors | Source |
|---|---|---|
| Radius · Earth radii | 13.1145 (+1.45717 / -1.23299) | Gravity Collaboration et al. 2019 |
| Mass · Earth masses | 3178.3 (+2224.81 / -1271.32) | Gravity Collaboration et al. 2019 |
| Density · g/cm³ | 7.74 | Calculated Value |
| Orbital period · days | 20815.6 (+1128.62 / -1128.62) | Zurlo et al. 2016 |
| Orbital semimajor axis · AU | 16.4 (+2.1 / -1.1) | Gravity Collaboration et al. 2019 |
| Eccentricity | 0.15 (+0.08 / -0.08) | Gravity Collaboration et al. 2019 |
| Inclination · degrees | 25 (+8 / -8) | Gravity Collaboration et al. 2019 |
| Irradiation · Earth flux | 0.0201 (+0.004 / -0.004) | Calculated Value |
| Equilibrium temperature · K | 1150 (+50 / -50) | Gravity Collaboration et al. 2019 |
| Stellar effective temperature · K | 7400 | Gravity Collaboration et al. 2019 |
| Stellar radius · Solar | 1.49338 (+0.049341 / -0.050935) | Konopacky et al. 2016 |
| Stellar mass · Solar | 1.51 (+0.038 / -0.024) | Zurlo et al. 2016 |
| Stellar luminosity · log Solar | 0.73347 (+0.01645 / -0.01535) | Konopacky et al. 2016 |
| Stellar age · Gyr | 0.03 | Gravity Collaboration et al. 2019 |
| Stellar metallicity · dex | -0.5 | Gravity Collaboration et al. 2019 |
| Distance · pc | 41.2441 (+0.1515 / -0.1505) | TICv8 |